Re: [PATCH_V2 1/4] dt-bindings: MIPS: Document xilfpga bindings and boot style

[Rob Herring]

On Tue, Oct 20, 2015 at 11:30 AM, Zubair Lutfullah Kakakhel
<Zubair.Kakakhel@xxxxxxxxxx> wrote:
> Xilfpga boots only with device-tree. Document the required properties
> and the unique boot style
>
> Signed-off-by: Zubair Lutfullah Kakakhel <Zubair.Kakakhel@xxxxxxxxxx>
>
> ---
> V1->V2
>
> Reformatted to 80 char column
> Correct clock phandle description
> Added digilent,nexys4ddr to get more specific about platform
> Added compatible string in example.
> ---
>  .../devicetree/bindings/mips/img/xilfpga.txt       | 83 ++++++++++++++++++++++
>  1 file changed, 83 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/mips/img/xilfpga.txt
>
> diff --git a/Documentation/devicetree/bindings/mips/img/xilfpga.txt b/Documentation/devicetree/bindings/mips/img/xilfpga.txt
> new file mode 100644
> index 0000000..eaba22b
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/mips/img/xilfpga.txt
> @@ -0,0 +1,83 @@
> +Imagination University Program MIPSfpga
> +=======================================
> +
> +Under the Imagination University Program, a microAptiv UP core has been
> +released for academic usage.
> +
> +As we are dealing with a mips core instantiated on an FPGA, specifications

s/mips/MIPS/

> +are fluid and can be varied in RTL.
> +
> +This binding document is provided as baseline guidance for the example
> +project provided by IMG.
> +
> +The example project runs on the Nexys4DDR board by Digilent powered by
> +the ARTIX-7 FPGA by Xilinx.
> +
> +Relevant details about the example project and the Nexys4DDR board:
> +
> +- microAptiv UP core m14Kc
> +- 50MHz clock speed
> +- 128Mbyte DDR RAM     at 0x0000_0000
> +- 8Kbyte RAM           at 0x1000_0000
> +- axi_intc             at 0x1020_0000
> +- axi_uart16550                at 0x1040_0000
> +- axi_gpio             at 0x1060_0000
> +- axi_i2c              at 0x10A0_0000
> +- custom_gpio          at 0x10C0_0000
> +- axi_ethernetlite     at 0x10E0_0000
> +- 8Kbyte BootRAM       at 0x1FC0_0000
> +
> +Required properties:
> +--------------------
> + - compatible: Must include "img,xilfpga","digilent,nexys4ddr".

Should be in the reverse order. Most specific comes first.

> +
> +CPU nodes:
> +----------
> +A "cpus" node is required.  Required properties:
> + - #address-cells: Must be 1.
> + - #size-cells: Must be 0.
> +A CPU sub-node is also required for at least CPU 0. Required properties:
> + - device_type: Must be "cpu".
> + - compatible: Must be "mips,m14Kc".
> + - reg: Must be <0>.
> + - clocks: phandle to ext clock for fixed-clock received by MIPS core.
> +
> +Example:
> +
> +       compatible = "img,xilfpga","digilent,nexys4ddr";
> +       cpus {
> +               #address-cells = <1>;
> +               #size-cells = <0>;
> +
> +               cpu0: cpu@0 {
> +                       device_type = "cpu";
> +                       compatible = "mips,m14Kc";
> +                       reg = <0>;
> +                       clocks  = <&ext>;
> +               };
> +       };
> +
> +       ext: ext {
> +               compatible = "fixed-clock";
> +               #clock-cells = <0>;
> +               clock-frequency = <50000000>;
> +       };
> +
> +Boot protocol:
> +--------------
> +
> +The BootRAM is a writeable "RAM" in FPGA at 0x1FC0_0000.
> +This is for easy reprogrammibility via JTAG.
> +
> +The BootRAM inializes the cache and the axi_uart peripheral.

typo

> +
> +DDR initialiation is already handled by a HW IP block.

typo

> +
> +When the example project bitstream is loaded, the cpu_reset button
> +needs to be pressed.
> +
> +The bootram initializes the cache and axi_uart.
> +Then outputs MIPSFPGA\n\r on the serial port on the Nexys4DDR board.
> +
> +At this point, the board is ready to load the Linux kernel
> +vmlinux file via JTAG.
> --
> 1.9.1
>
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